<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<script>
function boom()
{
  var p = document.getElementById("p");
  window.getComputedStyle(p, null).getPropertyValue("right");
}
</script>
</head>

<body onload="boom();">

<p id="p" style="position: relative; left: 3ch;">foo</p>

</body>
</html>
